1. Field of the Invention
The invention relates, generally, to low tire pressure warning systems for pneumatic tires mounted on the rims of automotive vehicle wheels. More particularly the invention relates to a device consisting of simple coordinated metal strapping, strapping seal and counterweight components used as a fixed mount for a known type of tire pressure sensor having a deflectable member and self-contained radio transmitter and power means within the drop-center of a tire rim without requiring modification of usual wheel rims so that the sensor may deflect within a tire mounted on a rim with each revolution of the wheel when the tire is going flat, to actuate the radio transmitter to broadcast low tire pressure alarm signals to a receiver located on the vehicle remotely of the wheel to thereby alert the vehicle operator.
The new device of the invention provides a metal strapping sensor mount that holds the sensor and its components in a fixed position in a drop-center rim and which strapping coincidentally mounts and holds the counterweight component of the device at a location on the rim to counterbalance the sensor. The counterweight and sensor thus are held securely by the new mounting device in fixed positions at all times and particularly during vehicle operation at speeds which may be somewhat in excess of normal, reasonable or lawful vehicle speeds.
The new device of the invention consists essentially of metal strapping, strapping seal, and counterweight components which are simple and inexpensive in construction, installation and use. Furthermore, the new device of the invention preferably is constructed so that only the strapping and seal are damaged, destroyed or discarded without loss of the counterweight when repairs of a flat tire are carried out at any place such as a usual tire repair service station. Thus, such service stations need only carry in stock usual metal strapping material and seals in addition to usual strapping tensioning and sealing tools, regardless of tire and rim size, thereby avoiding a requirement that each tire service station must maintain a stock of various sizes of counterweight components, in order to service tires and rims equipped with low pressure warning systems of the type described.
2. Description of the Prior Art
The problem of alerting a vehicle operator to the fact that a vehicle tire is going flat has existed for many years. Innumerable types and kinds of low pressure signaling devices have been proposed. These prior devices have utilized all kinds and types of sensors and signal transmitting means, including magnetic couplings, radio transmitters and receivers, and noise makers.
Tire and wheel balancing counterweights have been mounted exteriorly on rims. Counterweights have been held in place on a rim within the tire by an inflated inner tube pressing the counterweight against the rim. Other counterweights have been held by flexible bands spring tensioned about a rim so that the counterweights will move by centrifugal force outward radially of the wheel with each wheel revolution when a tire is going flat, and then snap back abruptly following such outward radial movements to produce a noise signal when striking the rim following snap-back.
Many types of sensors have been used involving deflection of a finger with each revolution of a tire going flat and having a powered radio transmitter activated by sensor finger deflection to transmit a warning signal. Such sensors have been mounted on wheel rims by bolts, welding or by elastic, stretchable or flexible bands with toggle latches for joining the ends of the bands. Also band tension adjusting means has been proposed for such flexible bands.
One example of a tire low pressure warning device is shown in Neu U.S. Pat. No. 3,154,048 which has a spring pressed bumper that is distorted or deflected each time it bumps the flattened road contacting portion of the tire when tire pressure drops during wheel revolution. The bumper is held in place on the rim by a flexible belt having a knocker which moves out radially by centrifugal force and snaps back against the rim during each revolution of the wheel when the bumper is distorted during low tire pressure conditions, thus producing a noise alarm.
The Hill et al U.S. Pat. No. 3,818,435 and the Church U.S. Pat. No. 3,835,451 each shows the same sensor of a type having self-contained power and radio transmitter components. These sensors are stated as being mounted on the rim with a threaded bolt or by welding. These sensors transmit low tire pressure signals when such low pressure occurs.
Snyder U.S. Pat. No. 4,117,452 also discloses a sensor having a deflectable finger and a self-contained radio transmitter. The sensor has mounting means consisting of a slotted bar engaged by pins and nuts carried by the rim for removably mounting the sensor on the rim. Alternatively, Snyder uses a flexible band to mount the sensor on the rim. The ends of the flexible band are joined with a toggle latch. Also, adjustment means to apply proper mounting tension to the flexible band is suggested.
All prior art low pressure warning devices of which I am aware have complicated structures which are difficult to install as new equipment at an automotive factory, or are difficult ato repair at a tire repair station in connection with repairing a flat vehicle tire. Further, the known prior art devices do not have a counterweight coordinated with a sensor of deflectable finger radio transmitter type by mounting and holding means which holds the sensor and counterweight in fixed relative positions during highway operation at speeds somewhat in excess of reasonable or lawful vehicle speeds.
Also, no known prior art device has any concept of a counterweight removably associated with the sensor mounting and holding means so that the counterweight is salvaged when the mounting means is damaged in connection with tire repair.
A need has long existed for a device for sensing and signaling the occurrence of low tire pressure during vehicle operation, which device includes a known type of deflectable radio transmitter contained sensor cooperatively removably assembled with a sensor counterweight; in which the sensor and counterweight are securely mounted on the tire rim and held in fixed positions in a drop-center tire rim with the counterweight oriented 180.degree. with respect to the sensor, in which only the sensor and counterweight mounting or holding means is destroyed and replaced when necessary to repair a flat tire, and in which the sensor and counterweight are reused during such repair.